title: Lyt-23+ cyclophosphamide-sensitive T cells regulate the activity of an interleukin 2 inhibitor in vivo.
abstract: Sera of thymus-bearing normal mice contain high levels of Interleukin 2 (II-2) inhibitor, whereas sera of athymic nu/nu mice do not. Evidence is presented that cyclophosphamide-sensitive Lyt-23+ T cells induce high II-2 inhibitor activity in the recipient nu/nu mice in the course of a graft-vs.-host reaction. The II-2 inhibitor has an approximately 50,000 mol wt. Its function is neither antigen specific nor H-2 restricted. During ontogeny, its activity parallels the development of T cell reactivity, i.e., it is absent both in the amniotic fluid and in sera of unborn mice, but increases to high levels during the early postnatal phase. The II-2 inhibitor described is viewed as an example of a T cell-dependent, in vivo regulatory mechanism able to effectively counteract the nonspecific activity of the Lyt-1+ helper T cell-derived II-2. Because the II-2 inhibitor activity is rather high in vivo, II-2 activity will exist only in close proximity to its producer cell, thereby maintaining specificity during the in vivo induction of cytotoxic T lymphocytes
mesh_terms: D000818:Animals; D003520:Cyclophosphamide / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic; D007375:Interleukin-1; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008819:Mice, Nude; D011506:Proteins / Q000378:metabolism*; D013601:T-Lymphocytes / Q000145:classification* / Q000276:immunology
chemical_list: D007375:Interleukin-1; D011506:Proteins; D003520:Cyclophosphamide